This control for 12 V drills was found in a 90s Elektor. The components are current, and Q1 can be replaced by a TIP42 mounted on a heat radiator.
This circuit is from a Japanese publication in 1967. The circuit uses a Geiger-Muller valve and...
Motorola's LM13600 integrated circuit is not very common today. The input voltage is 10 mV. We...
This circuit is from a 70s linear integrated manual. The integrated circuit used is uncommon today...